ἀντεργάτης

From LSJ

κεντέω τὸν πῶλον περὶ τὴν νύσσαν → of impetuous haste, goad the foal around the turning post

Source

Spanish (DGE)

-ου, ὁ antagonista, oponente πάσης τῆς ἐναρέτου πολιτείας ἀντεργάται Basil.M.31.640C.